Pedally controlled power-operated vehicle brake applying apparatus



o. H. BANKER 2,642,165 PEDALLY CONTROLLED POWER-OPERATED VEHICLE BRAKE APPLYING APPARATUS 2 sheetsg-sheet 1 June 16, 1953 Filed July 8, 1949 @W kw' E f. WMWN E w n@ .mW NNW WWU um. Kvm, sw mml ..-.i ww

INVENTOR. /la/z/ef WW SQQN SH @QN mx wmv mum@ NN AW Nm.

o. H. BANKER 2,642,165

2 Sheets-Sheet 2 PEDALLY CONTROLLED POWER-OPERATED VEHICLE BRAKE APPLYING APPARATUS June 16, 1953 Filed July 8, 1949 INVENTOR. @36x27 ',/Yayzef Pateted June 16, 195s 'UNITED STATES YPA'LENT OFFICE PEDALLY CONTROLLED` POWER-OPERATED VEHICLE BRAKE APPLYING APPARATUS Oscar H. Banker, Evanston, Ill., assignor to New Products Corporation, Chicago,

tion of Delaware Ill., a corpora- Application July 8, 1949, Serial No. 103,575

v 1 n This invention hasta do with a manually controlled power applied braking apparatus and relates more particularly to a lhydraulic braking Vsystem wherein there is a pressure booster unit manually controlled Yfor operating the master cylinder of the apparatus.

An important object of this invention is the provision of an improved hydraulic braking system whereinthe power forapplying the'j brakes is 4derived through a uid pressure source and controlled manually by a foot operated pedal normally 'having a small range of movement adaptingl this pedal to be disposed beside the 'conventional' accelerator pedal to facilitate easy and quick shifting of the operators foot onto the brake pedal. Y

Another object is the provision of an improved braking system employing a vhydraulic pressure booster which exerts the principal operating force upon the plungerA of amaster .cylinder together vwith means opposing braking applying advancement of the manually operated pedal with a diminutive force having a magnitude cQrrelated with the pressure in the ii'uid column between the master cylinder plunger and the brake applying pulsators.

` Still another object is the provision of an improved hydraulic braking system of the power type wherein a source of pressure fluid` for operating the brakes is maintained under pressure by either an'engine driven pump or a vehicle driven Claims.

(or 19a-"3) of the booster is immersed in a body of the circuit- Ycontained liquidto assure exclusion of air from pump should the other of such pumps be quiescent; and the invention further contemplates provision of a hydraulic accumulator as a component of the pressure fluid source so that uid can be stored under pressure for operating the brakes in the event of failure or quiescenoe of both pumps. Y l

. Another object is the provision in va power operated hydraulic braking system of coaxially arranged pressure booster and master cylinder units together with a valve and an operating rod there- `for disposed coaxially of these units for controlling admittance of operating uid to thev pressure booster unit and said rod havinga shoulder which contacts the master cylinder plunger for compression of the :duid column Vleading tothe brake pulsators incident to manual depression of the brake pedal should the brake booster be inoperative.

Another object is the `provision of a power op.- `erated hydraulic braking system according to the next preceding object wherein said manually operated valve controlling rod when advancedrfor l'manually applying the braking pressure is adsuch chamber. I

These and other desirable objects inherent in and encompassed by the invention will be more readily apparent from the ensuing description, the appended claims and the annexed drawings, wherein: n Y n Fig. l is a side elevational view partly in longitudinal section of a pressure booster and master cylinder assembled and arrangedin accordance with this invention, together with a diagrammatically represented iluid pressure source.

Fig. 2 is a side elevational View of the pressure booster and master cylinder units of Fig. l shown below a diagrammatically illustrated vehicle drivers compartment and diagrammatically illus- Vtrated mechanical and hydraulic connections with these units.

Fig. '3 is aview taken similarly tovFig. l illussubjected to sub-atmospheric `air pressure having Fig. 2. Beneath a oor board i iv of a drivers compartment i2 there is mounted a substantially conventional master cylinder unit i3 upon a part I4 of the vehicle frame by means of a bracket l5, formed integrally with the casingof such unit, and bolts i6 passing through this bracket linto anchored relation with the frame part. A conduit Il represented partly diagrammatically by a dotdash line communicates between the master cylinder unit I3 and branch conduits I8 and I9 connected with fluid operated pulsators 2l for operating diagrammatioally represented brake shoes 22 of the vehicle brakes.

A brake pedal 23 for controlling the master cylinder unit i3 is pivotally mounted at 2s upon a lower portion of an inclined floor boar" 25 in the forward part of the drivers compartment. This brake pedal is urged into the released position shown in Fig. 2 by a conical helical spring 26, and when in this position occupies a plane in contiguous parallelism with the plane occupied` by the vehicle accelerator' control pedal 2l which is pivotally mounted on the door board 2.5 at 28 and is connected with the vehicle throttle by a linkage 29 which may be conventional. A spring about a rod 3M of the linkage normally holds a slider collar 32h against a stop pin Silo so the operating lever 32d of the engine throttle (carburetor) is adjusted in accordance with endwise movement of the rod'. However, the spring is compressible to accommodate counter-clockn wise pivoting of the lever to the closed-throttle position by the plunger 32e of a hydraulic ram 32j when this rain energized though the rod 32a remains advanced to the left. The ram 333i is energizable by fluid under pressure received through aconduit 35g from a chamber 33 in a pressure booster unit 4t.

Brake pedal 23 is pivotally connected at 3l with a thrust link 32 which extends downwardly through an opening 33 in the floor board 25 into pivotal connection at 34 with the upper end of a .bell crank arm 35. A downwardly extending arm 36 of this bell crank has a spring 3l attached thereto and also anchoredrto a stationary part 33 `of the vehicle for urging the bell crank. 35-38 to pivot clockwise about a pivotal mounting 39 therefor in a floor-board mounting bracket lli. The lower end of the bell crank arm Si? pivotally connected at l2 with the forward end of a thrust link d3 which has a pivotal connection M at its rear end with an axially movable elongated valve operating element which projects into the pressurel booster unit d5. A flexible dust guard il oiers no substantial resistance to axial movement of the valve operating element 45.

hicident to depression of the brake pedal 23 counter-clockwise about its pivot 2e countercloclwise movement will be imparted to the bell crank :l5-3Sr about its pivot 39 for moving the thrust link the valve operating element i5 rearwardly (to the right as viewed in Fig. 2) for opening a control valve generally designated 43 in Fig. l. When the valve t8 is opened, duid from the pressure uid source generally designated 49 in Fig. l is communicative through a conduit 5l and said valve it with the interior of the pressure booster 45 for causing this pressure booster to exert mechanically applied force to a plunger 52 (Fig. 1) of the master rcylinder to compress a liquid column in the conduit il for applying the vehicle brakes. The quantity of fluid allowed to enter the pressure booster 4E through the conduit 5l from the pressure fluid source is determined by the amount of depression of the brake pedal 23 and consequently the distance the brake pedal is depressed. determines the rmness with which the brakes are applied. No fluid can be dissipated from the source @i9 excepting the metered quantity when the valve 48 is open. Inasmuch as the force necessarily applied to the braise pedal. 23 is primarily a controlling force for controlling the valve lua relabe returned to the position illustrated in Fig. 2.

Details of a typical master cylinder structure are shown in connection with the master cylinder I3 in Fig. l. This structure I3 embodies a cylinder proper superposed by a reservoir 5S having a filler opening 5l `closed by a removable plug 58. The outer end of thev cylinder 55' has a coupling element 5S threaded thereonto. This coupling element contains a central bore El of which a portion is threaded at 52 for receiving a iitting 63 having a bore t4 communicating at its outer end with a threaded stem 55 of a fluid pressure operated switch SW for controlling the vehicle brake signal lights (not shown) A lateral passage E2 leading from the .bore S4 communi- -cates with an annular passage t1 of a conduit coupling 68. The conduit l1 communicates with the annular passage 6l and leads from the coupling 68 to the brake actuating pulsators 2l as illustrated in Fig. 2.

Brake -iluid (not shown) in the reservoir 55 feeds downwardly through a replenishing port 69 in front of the plunger 52 when this plunger' is retracted into the brake releasing position shown by a spring l! reacting between the fitting 59 and a spring retainer cap 12 which bears against the plunger 52.

In a conventional vehicle installation lof the master cylinder i3 a linkage from the brake pedal Vinthe operators compartment is directly connected with the plunger 52 so that when the pedal is depressed the plunger 52 will be forced rearwardly or to the right as viewed in Fig. l, by direct manual eiort. When this occurs the plunger will compress the fluid column in the cylinder bores el and 64, lateral 5S, groove and the conduits il, ill and I9 .to actuate the brake applying pulsators, 2i. In the present installation however pressure developed by the pressure booster 't5 under manual control of the brake pedal v23 is employed for advancing the master pedal plunger 52 Vinto the brake applying position.

The pressure booster or pulsator i6 comprises a large diameter cylinder 'I3 of which an end Wall 14 is formed integrally with the cylinder 55 and reservoir 56 of the master cylinder unit. A ring of bolts I5 secures the end wall 14 to the cylinder '13.V A piston 16 reciprocal in the cylinder 13 is urged into the axially retracted position shown by a helical spring 1l. A tubular stem 18 of the piston 16 extends slidably into a bore 19 of'the cylinder end Wall 14 and into separatable engagement with the left end of the master cylinder plunger 52. Therefore when the piston 1S is forceably advanced to the right it will advance the master cylinder plunger 52 for applying the vehicle brakes. Fluid under pressure from the source 49 is admitted to the left end of the cylinder 'I3 behind the piston '6 under control of the control valve 42. The control valve i8 comprises a circumferential port Bl in the form of an internal groove in the pistonstemi and respectively communicable through axial passages 82 (onefbeing shown in Fig. 1) with the space between the left end of the piston 'i6 and the opposed end wall of the cylinder 13. Complemental elements of the control valve 48 are a land 83 circumscribing thevalve operating element 45 and an adjacent groove 84 likewise circumscribing the element 45. An axial bore 35 in the tubular element 45 communicates with the annular groove 84 through a plurality of circumferentially spaced ports 86 of which one is shown. The valve 48 is shown in a pressure releasing posi- .Fluid from the sump l through a conduit ||2 by la vehicle driven pump tion wherein uid can exhaust fromthe annular .chamber 80 through the passages 82, port 8| and 1 it can be seen that the return line fitting 9| is at higher elevation than the port 89 wherefore I this port will always be immersed in the liquid to insure no entry of air into the pressure cham ber 80 with attendant erratic delaying effect when liquid under pressure is introduced into the chamber 80 to cause the next brake applying stroke.

Valve operating element 45 extends axially into la bore 93 in the master cylinder plunger 52 into contact with the spring retainer cap 12. vA snap ring 94 in the left end of the bore 93 cooperates with a shoulder 95 of the valve operating element Ato prevent withdrawal of said element from said plunger.

Any brake fluid leaking past the enlarged right end 95 of the brake pedal plunger 52 is returned to the reservoir through a port 91.

An oilseal in the form of an O-ring 98 prevents leakage of oil from the reservoir 56 into the F tubular'stem', 18 where it would co-mingle with the hydraulic fluid used in the pressure booster and vice versa. This same function is also served by an O-ring backed by a leather ring |00a, both disposed in a groove |002; in the plunger 52.

An O-ring type of seal 99 prevents'leakage of' fluid from the pressure booster unit between the tubular valve operating element 45 and the bearing |0| therefor in the left end wall ofthe cylinder 13.

The source 49 of pressure iiuid for actuating the pressure booster communicates through the conduit and a tting |02, carried by the outerv end of the valv'e operating elementY 45, with the bore 85 within such element 45. Thesource of pressure fluid includes an engine driven pump |03 which draws `fluid from the sump |04 through a conduit |05 and `discharges the fluid through a conduit |06, a switching valve |01, va conduit |08, and a check valve |09 into an accumulator |04 is also withdrawn 3which is adapted-to discharge Vthrough a conl. duit |4 and the switching valve"|91, said conduit |08 and the check valve |09 into the accumulator I. Apressure relief valve |5 is connected between the low pressure and high pressure conduits |05 and |05 and a similar pressure relief valve IIB is connected between the low pressure and high pressure conduits ||2 and 4.

Assuming the vehicle engine is at rest and that the vehicle Ais coasting, only the pump |.3 will be operating Wherefore the pressure of fluid in the conduit |4 will prevail over that in the conduit |06 and shift a ball |1 axially of a cylindrical bore |8 in the casing ||9 of the switching valve |01 into the position shown where the b all is effective to prevent discharge of fluid from the conduit ||4 through a port 2| wherefor uid fromthe conduit |4 will be available to replenish the uid supply in the accumulator 49. Excessof uid flows through the pressure relief valve H6 to the sump |04. y

Assuming the vehicle to be at rest vthe pump I3 the pump |03 will be operable to draw uid from both pumps |03 and ||3 are operating the ball ||1 may occupy any position within said bore without preventing a supply of fluid from at least one of the pumps to the accumulator Operation of the apparatus The present apparatus employs an essentially conventional master cylinder unit |3 from which a column of brake operating uid is impressed through 'conduits |1, la and |9 to the brake actuating pulsator units 2| associated with the vehicle wheels (not shown) when a master cylin- V der plunger 52 is moved rearwardly or to the right as viewed in Fig. l. Such movement oi the master cylinder plunger is normally primarily incurred by force derived from fluid under pressure` from the source generally designated 49 in Fig. 1 and by operating the pulsator type pressure booster unit 46 under'control of a brake pedal 23 Fig. V2in contiguity with an accelerator pedal 21 in thel drivers compartment I2 of a vehicle. The pressure fluid source 49 includes an accumulator in which a supply of fluid is maintained under pressure by a check valve |09 when neither of two pumps |03 and H3, respectively engine driven and vehicle driven,y is being operated. Either of these pumps or both thereof are operable for supplying` u uid to the accumulator Ythrough the switching valve unit |01.

The drawings illustrate the apparatus in the status allowing the vehicle brakes to be released` With the control valve 48 Fig. 1 in the position shown, fluid under pressure from the accumulator 'i reaches the groove 84 of this valve through the conduit 5| and the bore 85 of the valve operating element but can flow no farther.

The spring 1| in the master cylinder 55 will have returned the plunger v52 to the position shown and the spring cap 12 will have pressed against the right end of the valve operating element 45 for retracting this element into the position shown. rl'his retractive movement of the element 45 caused the circumscribing land 83 thereon to have uncovered the valve port 8| to establish communication of the pressure booster chamber 80 with the pressure booster chamber 90 throughthe channel 82, said port 9|, opening 81` and theport 89 thus facilitating retraction ofthe piston 16 into the position shown under the force of the spring 11.

When it is desired to apply the brakes the op- `crater will depress the brake pedal 23 by pivoting it countercloekwise about the fixedr pivot 24 A and thereby cause rearward motion of the valve operating element 45; This will rst move the valve 48 into a closed position wherein the y land 83 enters the opening 81 toprevent communication between the pressure booster chambers and 90. Thisl movement of the valve operating element 45 is yieldably yopposed by the spring 1| inthe mastercylinder 55. Continued depression oi the brake pedal and attendant rearward movement of the operating lelement 45 vwill establish registration of thel will'be idle butif the vehicle engine is running valve'groove 84 with the port 8|.

Fluid under .-lrfssu willvillen. 110W .-.intQz-the-.nlessul'e..resister @member-8'3- Tl-11S. geeewlwretw l. to. move rearwardly against the f oroe ofA thel Asitting A 11 t, and to press the right-endof fthe tubular stem 1S. against the letend-of the master cylinder plunger 52. This movement of the pistonl 'lli .landof the plunger 52 will ceasewhenthepistonrmoves Ifar enough to vcarry `theport '8|'. out yof V'registry with the'groove .34 and into registry withthe land 83. `.Consequently the advance'of the piston .l and plunger 52 vfor applyingA the vehicle bralges willbein an amount correlatedl with the manual advance `of the kvalve operating element .45. llhe voperator. theretore responds conventionally to apply p the vehicle brakes with a rrnness correlated with the amount of depression of the brake. pedal. j Para. tial release of thefbrakes is possible-byV partially releasing the brake pedal tof allow -the-valve- ...operating element 45 to retract under Athe force columnlhermagnitude ofthe diminutive reactiv e f orce -exerted by the fluid on the rightgendof the 0D-- Ieratingelement 45 .can .be varied in. .accordance vvi th`l the diameter of such element. However, this diminutive force will always be vproportional Ytto the force, with. which.. the brake shoes are v frctionally applied to the .vehicle brake drums wherefore rthe operator of the. Vehiclewill have @necessitate Sense :,Of .the arrlcumtA of braking force.beingy applied. This is contrary to the .,cgoritrol .characteristics of a ,control valve .Cor-

'.lo'f the spring 'll-and pressure offmthe fluid, co1- fumn Yin the master cylinder `55 to move the-land ['83 forwardly v(to the left)v from the openingl 81 `tofallow .exhaust of Vfluid from the-pressure booster. chamber 80- through the valve Vlli-l into the chamber Si). Y tractive motion of` the` pistonJE bythe spring L'll' and the pressure. of fluid inthe cylinder 55 against ytheplunger .52 andthe right end of the .tubulanfstem 13. This retractive moti-on of the `piston i6 will ceaserwhen the opening 81 com- A.mences .to telescope `over the land B3 of the partially retracted valve-operating element 45. Complete release of .the-,brakegris attained by complete. releaseof the. brake pedal 23 so that the piston. 31Sl completely retracts before itcan carry the, opening. 8'!k telescopically l overv the .valve land 33. Any leakage of. fluid between the pistone-'IiiV and the cylinder .wall 'liwhich wouldlcause. an excess of uid in the pressure booster chamber Suis accommodated by the conduitez which conducts the excess uid` into the common sump lull for the pumps 103. and H3.

.A pressure limiting valve unit Ill() in the work .memberjl allows huid to escape through passage MI. should .the source be one-capable of i developing .pressure in excess. of a Vpredeter- .mined value, say 30 lbs./sqare.inch. This as- -eures thepressure ,booster unit capability of operating without applying the vehicle brakes too suddenly irrespectively of the pressure of a .tand-ard equipment source upon aV vehicle.

One.; advantage of the presentapparatus is the .feature of providing resistance to depression of .thefbrakcpedal 23 as adirect function` ofthe factualbrakingforce incurred by `the brake shoes 22.,vvhile'.causing such'resistance .todepression .of thenbrakepedal to be significantly less than that incurred .byconventionalbraking systems. It caribe observed in Fig. lV that during applica- `tion of the brakesy with a forceproportional to thepressure of the fluid column of which a por- .tion is in the uidcolumn confining means 55, 'such-pressure of the fluid column is impressed Aupon-.theright end of the valve operating elementl 45 to urgethis element retractively. a But .because of the end area of theelement 45 exposed tothe Yiluidvcolumn being substantially less Vthan theV cross sectional area of the bore of the master cylinder 55 the total force exerted end- .wise on the element 45 by the column of brake nuid willlbe correspondingly Vless than would be vnecessary to advance andhold a conventional 'm'aster .cylinder plunger in thebrake applying .position VIn the present apparatus rthe master 'cylinder plunger 52 is advancedY by mechanical This Yoccurs attendant to `reresponding to the` valve 48, but adjust ed solely in opposition to .a spring which Wouldcause .the .resistance to depression of the brakepedal to increase indirect proportion tothe distance it is depressed. VASuch resistance of a spring would not necessarily have a magnitude correlat- .v ed with the amount of braking QICC ncurredfor everyposition of the brake pedal.

Another Vadvantage of the present apparatus becauseofthe diminutive reactionforce ofthe brake fluidupon the valve operating element 45, is. the convenient and practicable use of a brake pedal requiring av smaller range. of motionwith reference to 4that required for the conventional brake pedal.V Because of the relatively. small .force .required for. aflvarlnrie the .Valve ,Operating element, 45 there needs to be correspondingly lessmechanical advantage incurred by the linkage interposed between the brake pedal and the valve operating element. Consequently this Alinkage need not incursubstantial motion diminishing action forthepedaL Wherefore a relatively small movement of the pedal will be efec- `tive `for controlling the valve. Consequently the motion range of the brake pedal can correspond substantially to that of the conventional accelerator pedal. Y This facilitates placingthe brake pedal andthe accelerator pedal in close proximity to provide convenience for the operator in shifting his ,foot selectively between these two pedals.

'lfhe proximity of the brake pedal and accelerfator.` pedal is such vthat an operators foot can :simultaneously depress these pedals, but the v auxill-iary throttle ,control shown in Fig. 2 is operable.n under control of the brake applying Iniecha-riism to close the throttle despite throttle opening tendencies of the depressed vthrottle pedal. ns soonas the brake pedal 23 Ais deH pressed, and before it Acan reach tothe level of the accelerator pedal 21, the attendant increased pressure in the chamber 8U is communicated to the ram 30j whereby its plunger 39e pushes the throttle vlever Sdfinto the closed throttle positionagainst lthe compressedloadof spring 30 if the rodSanhasbeen moved to theleft by derprerssion of the accelerator pedal. This will eliminate the. necessity of the driver .being careful not to have his lfootiover theaccelerator pedal when pressing the brake pedal.

-As wear occurs upon the. frictionzsur-faces of -I the brake shoes this willbevreflected conven- -tionallyto the operatorbvthe brake pedal be- -ing depressed a correspondingly-greater distance before the brakes commence 4to l be applied. However, because of the-entire operating range of the brake pedal being less than the brake -pedal of conventional manually operated master cylinder units, the .initial movement of the brake pedal before Vcommencing to apply brakes with the apparatus of enabling the operator to engage thebrakes by manual force applied directly through the brake pedal 23. In the normal operation of the apparatus a shoulder |25 upon.'

the Valve operating element 45 -is not advanced farenough to abut the left end of thefmaster cylinder plunger 52, this being becauseof the valve 48 being rst operated to admit pressure the tubular stem 18 advances the plunger` 52 more rapidly than the shoulder |25 can approach saidwplunger. In the event of failure vof the pressure uid source 49, however',y the shoulder |25 can abut the plunger 52 whereupon by pressing abnormally upon the pedal 23 the operator will be able to-advance the brake fluid column forapplying the brakes. l Y

A further `advantage is the employment of the accumulator |||vin theluid pressure source so that ,in the -event of failure of either pump to operate. when it is desiredto obtain power application of the brakes there will be sufficient fluid stored inV this accumulator for applying the brakes a plurality of times.

A'modie'd form of the invention shown in Figs. 3 and 4 employs a pressure booster unit |5|fenergizedA when subjected to sub-atmospheric air pressure having its source for lexample at an intake manifold |52 of aninternal combustion engine (not shown). The engine draws air successively through a diagrammatically shown aircleaner |53 and a carburetor |54. vA low pressure conduit |55 leading from the intake manifold connects with a check valve |55 which is connectedby'a conduit |51 with a diagrammatically illustrated accumulator |58. -A flexiblfe conduit .|59l communicates between theaccumulatorahd an axial bore 16| in a valve operating member 62 corresponding to the valve operatingmemberf45 in the rst embodiment.A

In this4 case, however; the bore in the valve operating rod is connected with the low pressure side of the uid energy source. The high pressure side of the fluid energy source is `at atmosof a piston type Work member in a second chamber |16 of the pressure booster unit. The most rearward end, the right endY as viewed in Fig. 3, of the member |62 projects slidably into a bore 93 ina plunger 52' of a master cylinder unit I3. This master cylinder unit I3' is essentially like-the master cylinder unit |3 of the ls't embodiment wherefore to expeditethis disclosure, all corresponding parts of this unit will be simply designated by the same respective reference characters as the Fig. 1 embodiment but with Athe vaddition of a prime.

Work member |15 divides the cham-ber |16 into a high pressure chamber section |11 and a lfluid into theA master cylinder chamber 88 Sovthat Y low pressure chambersection |18. Work memfber |15 `contains radial ports` |1I corresponding to ports |1| and an internal groove-like port |12 corresponding to the port |12. This port |12 communicates with the high pressure chamber section |11 through axial por-ts |13' corresponding to the ports |13 in :the stem |68.

Stem |14 is axially slidable Within the cylindrical inner periphery of an annulus |19 constituting the inner element of an oil seal uni-t |8| held in fabricated assembly with an end Wall |82 of the chamber |16 and with a ange |83 of the master cylinder unit by means cfa circle of bolts |84 of which one is shown. Inasmuch'as the inner periphery of the oil seal element |19 is smaller in diameter than the bore of the master cylinder 55 and is in contiguous coaxial relation therewith such inner periphery is tantapheric pressure and communicatesY through a conduit Vltrleading from'the air cleaner |53 to a champel-section'` |64 Aat one side of a piston typework member`|65 in a chamber |66 of the pressure booster unit |5`|. Chamber section |64 is l.a high pressure section' whereas aj section |61-at the opposite-end of the piston or workr member is a low-pressure section.

The booster unit piston |65 includes a tubular stemY |68 having an enlarged end portion |69. This enlarged endportion of kthevvork member stem j|68 has a"Y plurality offradial'ports 1| communicative 'with the interior of such stem; seeFigll.- 'An internalicircumferential groove or portv |12-in the enlarged'endportion |69is spaced `axially from the circle of' ports l1'lv`and communicates `vwith the chamberv section |64 through a series of axial ports |13 'which'alternate with vthe radial portsV |1| circumferentially of `the 'stemas illustrated in Fig. 4.

The'valve 'operatingmember |62. extends axially'through'fvthepwork memberstem |68 and through e Corresponding we .member stem .H4v

mount to .and'therefore can be regarded as a reduced diameter portion of the master cylinder bore. In other Words, the annulus |19 of the oil seal unit |8| in providing a sliding seal relation with the outer periphery with the work member. stem |14 functions similarly to the -bore 19 in the first embodiment and which valso can bek portion of the regarded as a reduced diameter bore of 4the master cylinder 55.

The right end of the work member stem |14 is separably abutted againstthe left end of lthe master cylinder plunger 52. A radial Iiange |85 of the valve operating element is abuttable against a shoulder |86 formed internally of the hollow stem Ito limit retractive endvvise movement of the valve operating member. This ange and a large diameter land portion |81 `of the valve operating member are traversed by an axial groove |88 in said member which provides a breather passage for an annular space |89 bee` tween the left end of the plunger 52' and -the stem |14.

A plurality of radial ports .|9l (one being shown) spaced circumferentially about the valve operating member |62 communicates between .the

bore |A6| in this member and a circumferential groove-like port |92 which is spaced axially from a groove or recess-,|93 circumscribing said'member |62. A rib-like land |94 separates the` circumferential port from the recess |93. Elements |9I, |92', |93 and |94' respectively corresponding4 to the just-described elements vISH-|94 are formed in the member |62 for cooperation with valve components |1| and |12 in the work member stem periphery of the stem |68.

Operation of the second embodiment the intake manifold |52 -is associated to 4be oper- A |68. An oil seal unit |95 is securedv tol an end wall |96 of the chamber |66 Ifor establishing a sliding sealing relation with the outer`v ating, a low pressurecondition will becreated in the intake manifold, and this will be Acommunicated through thecond-uit |55, the checliv Valve |56, conduit |51., the accumulatorl, and

the flexible conduit |59 with the bore |6,| of the valve operating memberV |62. Sub-atmospheric pressure will thereby be communicated ,to` the circular ports |92 andV |62', butwithout effect,

inasmuch as they are sealed closed by the inner periphery of the hollow workmember stems |14 5 and |68.-

Ccncurrently, substantially atmospheric pressure will be communicated from the air cleaner |53 through the conduit |63.into lthe chamber. section |64. Atmospheric lpressure is also maintained in the chamber section |61 because cf communication between the chambers |64 and |31 through the axial ports |13, the annular -port |12, the `bridging recess |93' in the .valve operating member, and the radial ,ports |1|- Atmos-U pheric pressure is also present. in the. chamber sections |11 and |18, communication being had between the atmospheric pressure .chamber section |64- and the chamber section .|11 through one or more ports 26| in the forwarder left end portion of the cylindrical wall of the chamber |66. r Communication is provided between the chamber sections V|11 .and |18 by the axial .ports |13', the annularport ,|12., annular bridging. l

recess 93, and the radial ports |1|'.

Inasmuch as the various sectionsof the work.

member chambers ..|66.and |16 areintereommunicating, the spring. 1| in the master cylinder can expandtopress theplunger 52 forwardly-or to .-the..left, as 1Viewed in Fig. 3, to

force the work member |15 andl its. stem |14 forwardly into the position. shown.V This causes displacement of the work `member and its stern 168 forwardly since the stem |68 -abuts against the left endiof .the work member |15 at 262.

When..the.,operator wishes .to apply. the vehicle brakeshe.will. press upon apedal corresponding` to the brake pedal.- 23 in Fig. 2, whichis connected througha linkagercorrespondingrto ,that shown.V

which corresponds .to the ,brakeoperating mem. ber` 45 inthe nist-.describedembodiment. Thiswill cause the operatingmember |62 .-to be moved .Y

to the right, .whereu-pon the circular..lands |94` and |94'. :upon such member will rst close theY willsimultaneously carry. the. annulariports or recesses.|52 Aand |92 into registryrespectively.- f with ythe ports |1|' and |1|, Whereuponia pres-y J sure .differential will be simultaneously.l created.V upon theopposite ends of the work members- |15 land|65, since the chamber sections A|18 and |61 will -then` be establishedin communication .with

the sourceof sub-atmospheric. pressure. at Vthe intake manifold |52. Therefore, the .work mem.v d bers |15 and |65 will be causedY to simultaneously advance to the right underthe influence of the predominating air pressure in the chambersections |11 andv |64.- vTherear endof the stem-v |14y will thereby be caused ito press againstthe forward end of the plunger 52 .both by the `force of air pressure upon the left .endof thefwork member |15 and upon the left end of the work member |65, sincethe..steml68 of vthis latter work member will be caused to exert force upon theleft `end of thework vmember. .|15 at 202.H

When the .brakes have gbeenfappliedfwith 4the f desired force, the operator ceases advance of the |62 whereupon :the work members. |15 and |65'.Willterminate-their.x advancement bycarrying the ports1|1|f and .I1 I.

valve-controlled member into registry with the lands |94 and |94.

Should the operator desire to apply the brakes` with greaterforce, he, will simply depress. .the

river-in registry with the lands |94 and |94'.

Partial releasev of the brakes is accomplishedbypartial retraction of the control member |62 Y and'carrying the annular recesses |93|93' into bridgingfrelation with the ports |12-|1| andI When this is done, communicationfis established between the chamberl pressed iluid in the master cylinder-55'- can force Y' the master cylinder plunger 52 retractively to the leftl together with thegworkmembers r|15 andl |65, incident to air flowing from--'the chamber v section |11 through the axial ports-|13", -annular port- |12,' bridging recess |93; fand' the radial ports |1|. At the same time, air flows from the chamber section |64'throughY-the axial port |13,

annular port |12,'bridgingrecess |93' and theV radial ports |1| into chamber section |61. 'When'y the master cylinder plunger andthe Work members 15-'and |65 havebeen retracted a distance correlated withthe manually, controlled retrac tion of the valve control memberl62; the .ports |1|' and |1| 'will 1 arrive in registry with the lands |94 and |94; to maintain the status of partial brake engagement.

When it is desiredxto 'completely'releaseI the brakes, the operator. will conventionally' release the brake pedal, causing complete retraction of the valve operatingmember |62 into the posi-,j tion shown in Fig, sorthat ensuing complete retraction of the master cylinder plunger 5,2k and of the workr members |15 Yand |65 cannot retract4 therradial ports |1|,. and, |1| into registrywith the annular lands |94 and |94.

During ,depression of the'gbrakev pedal for causing applicationV ofthe brakes, there is a physical manifestation .to the. operator of the force being mechanically exerted. upon the master cylinder plunger 52'; in the samemanner as explained ,l above in the first'r embodiment.v vThis pressure manifestation istransmitted to theright .Ar end of the valve-operating member-|62 bythe...y pressure of uid in .the master. cylinder, and this.

beingbut a fraction of the-total force exerted upon. the ,brakev cylinder-.fluid by -the master. cyllnder becauseuof .the` vright end area vvof the control, ,member |62 being lessgthanthe'right en d area .of the` plunger 52'. Y y miniature force transmitted reactively from the brake' `fluid throughtheA ,valve-operatingr member .V to the foot of the operatorupon the brakepedal n can beselectively.,predetermined in accordance withthesizepf thegbore 93in the plunger 52T, w1thV respect to the 'bore of the master cylinden Should the 'source of subatmospheric air pressure fail, 1t is possible'for the operatorto manual..

ly advance the'master cylinder plunger 52 for This/can occur ,by .the

engaging the brakes. annular-flange |-v on the valve-operating mem- The ratioV of this wel@ berv being advanced into engagement with the left end of the plunger 52', whereupon continued depression of the brake pedal will cause the member |62 and the plunger 52' to advance in concert for compressing the uid in the hydraulic brake system. During this concert advance of the operating member |62 and the master cylinder plunger, there is no impediment to such movement Iby either of the work members |15 or |65, inasmuch as the breather passage |88 provides communication between atmospheric pressure in the air cleaner |53 and the annular space |89, which is expanded pursuant to advance of the master cylinder plunger from the rear end of the work member stem A| 14.

Having described a limited number of embodiments of the invention with the view of concisely illustrating the same, but without intentionof limiting the scope of the invention to-less than the boundary imposed by the prior art, I claim:

1. In a braking and throttle control system forY a vehicle having brakes and driven by anengine of which the power output is controlled by a throttle; a throttle control pedal operably connected with said throttle and having a foot pad depressible for normally opening the throttle to increase thel engine power output; a brake control pedal having a foot pad, said pedals having j release positions wherein said pads are substantially in a common plane and being disposed suiiiciently contiguous that'an operators foot can engage them both for simultaneous depression; a Asource of liquid under pressure; a hydraulic pressure booster comprising a chamber and a work member subjected to the pressure of uid in such -chamber and advanceable thereby when the chamber is communicative with said source; means including -a valve adapted to establish communication 'between said source and said chamber; f'force transmitting means interposed between said work member and the vehicle brakes for applying thereto an operating force in accordance with the amount of advancement of said work member; means yieldably urging the valve into a neutral position wherein it precludes Vcornmunication between said chamber and said source; a manually advancea-ble memberl connected with said valve and operable when advanced for opening the valve to establish communication between said chamber and said source, said work member being advanceable relatively to said manually advanceable member responsively to such communication to replace the valve into said neutral position incident to advancing a distance correlated with the distance of advancement of the manually advanceable member; means for applying to said manually advanceable member a diminutive retractive force proportional to the operative force appliedv Vto the brakes by said work member; means connecting the brake pedal with said manually advanceable valve operating member to advance the same pursuant to depression of such brake pedal; and means operableresponsively to an invcrease of pressure in said chamber to a value less than that required for advancing the work member to prevail over said accelerator pedal for closing the throttle. v

v2. The'combination set forth in claim 1 whereinthe means operable responsively to an increase ofV pressure in the pressure booster chamber comprises a hydraulic ram including a plunger disposed for closing the throttle-when the ram is subjected to fluidunder pressure, anda conduit communicating kbetween said ram v and said chamber.

'3; The combinationset forth 'in claim 1 wherein the operating means interconnecting the brake pedal and said lmanually advanceable valve operating member possess motion diminishing characteristics not substantially diminishing the motion imparted to said member relatively to the motion of the foot pedal pad.

4. In a braking system for hydraulically operated brakes, a master cylinder, an axially bored plunger advanceable axially in said cylinder to compress fluid therein vto effect brake operating energization of such cylinder and plunger, 'ai

pressure booster unit comprising an axially bored work member advanceable axially against the plunger to advance the same pursuant'to energiation of the booster unit during admittance of energizing fluid thereinto, valve means ma-A nipulatable tol admitV fluid into the booster unit, j

a valve operating f element projecting axially through the work member bore 4into the plunger.y bore and advanceable therein to manipulate the causing the master cylinder'plunger to be axially advanced by and withsaid valve operating element independently of movemetnt of the work member pursuant to advance of said element beyond the valve-operating range should the pressure booster fail to energize.

5. The combination set forth in claim 4:,k

wherein an end portion of the valve operating element projecting into the plunger bore and of less transverse area than they transverse area of the plunger islexposedA to the brake-operatingr fluid and thus adapted to be urged retractively therebyjfor manifesting to the operator the magnitude of brake-operating force exerted by the master cylinder.

6. In a braking ,system for fluid operated brakes, fluid column conning means including a master cylinder andan axially bored plunger axially advanceable in such cylinder to compress suchv uid column to a brake-applying pressure, a source of uid at non-atmospheric pressure, a pressure booster unitvcomp'rising an axially bored work member separable from the master cylinder plunger but axially advanceable into force transmitting relation with respect thereto to advance the same attendant to energization of the booster unit pursuant to communication thereof with said source, valve means manipuy latable to establish communication between the booster unit and said source, said valve means element projecting through the work. member bore into the plungerbore Where an end portion` of less transverse area than the plunger is ex- I posed to the'interior 4of the fluid column conflningmeans, said valve-operating element being movable axially in saidlbores, the manually controlled component of the valve means being constrained for movement with said control element to cooperate with the first component in establishing said communication when the control element is advanced, in terminating such f' a valve-operating.

17 sion of the brake pedal pad a` distance unexceeded by the operating range of movement of the accelerator pedal pad; and means operable responsively to partial energization of said brake applying unit to prevail over said accelerator pedal for closing` the throttle in the event of said pedal pads being simultaneously depressed.

OSCAR H. BANKER.

References Cited in the lle of this patent UNITED STATES PATENTS Number Name Date 1,781,869 Bragg et al. Nov. 18, 1930 1,919,930 Cash July 25, 1933 2,006,487 Sorensen July 2, 1935 2,090,152 Porter Aug. 17, 1937 Number 

